1. Field of the Invention
This invention relates to stabilized distillate fuel oils. More particularly, this invention relates to inhibiting color deterioration and particulate formation in distillate fuel oils, such as diesel fuel.
2. Description of the Prior Art
Various middle distillate fuel oils, such as diesel fuel and kerosene, tend to deteriorate with time. This deterioration usually results in the formation of sediment, sludge, or gum and objectionable color deterioration. Sediment formation may cause clogging of fuel system equipment such as filters, screens, nozzles, burners and other associated equipment. Discoloration of distillate fuel oils is objectionable for various reasons, including customer's preference for light colored fuel oils because discoloration may indicate that deterioration has occurred.
Suggestions of the prior art for stabilizing fuel oils include U.S. Pat. No. 2,672,408, Bonner, which discloses the use of oil-soluble water-insoluble amines, the general formula of which can be represented as: N(R).sub.3, wherein R can be hydrogen or the same or different hydrocarbon radicals with at least one R being a nonaromatic hydrocarbon radical, for protection of particular blends of liquid hydrocarbons against discoloration. U.S. Pat. No. 2,945,749, Andress, discloses the use of a tertiary alkyl, primary, monoamine having from about 4 to 24 carbon atoms and in which the primary nitrogen atom is directly attached to a tertiary carbon atom, for inhibiting fuel oil deterioration during storage. U.S. Pat. No. 3,049,414, Kruyff, discloses a process for stabilizing the color of gasoline comprising the steps of washing the gasoline with a liquid characterized as being free of heavy metals and capable of dissolving pyridine; washing with alkaline aqueous solution, characterized as being free of heavy metals; removing substantially all the free alkali; and then adding an organic nitrogenous base, all of whose carbon-carbon bonds are saturated. U.S. Pat. No. 3,186,810, Dunworth, discloses a distillate hydrocarbon fuel oil containing a certain oil-soluble, basic amino nitrogen-containing addition type copolymer and an N-substituted cyclohexylamine in which the substituents consist of 1 to 2 alkyl groups of 1 to 4 carbon atoms. Also, U.S. Pat. No. 3,336,124, Dunworth, discloses a distillate hydrocarbon fuel oil containing certain oil-soluble polymeric dispersants and an N-substituted cyclohexylamine in which the substituents consist of 1 to 2 alkyl groups of 1 to 4 carbon atoms.
Of primary interest is U.S. Pat. No. 3,490,882, Dunworth, which relates to stabilized petroleum distillate fuel oils containing N,N-dimethylcyclohexylamine and, optionally, an N,N'-di (ortho-hydroxy-arylidene)-1,2-alkylenediamine. U.S. Pat. No. 3,640,692, Rakow, et. al., discloses a stabilized distillate hydrocarbon fuel oil composition comprising a major proportion of a distillate hydrocarbon fuel and a minor proportion of a stabilizer comprising (a) an additive selected from the group consisting of (1) an amide plus a Schiff base; (2) an amide containing a Schiff base group; and (3) an amide containing a Schiff base group in combination with either an amide or Schiff base; and (b) a cyclohexylamine selected from the group consisting of N,N-dimethylcyclohexylamine and dicyclohexylamine. Also, U.S. Pat. No. 3,701,641, Rakow, et. al., discloses a stabilized distillate hydrocarbon fuel oil composition comprising a major proportion of a distillate hydrocarbon fuel and a minor proportion of a stabilizing additive comprising (a) a polyamine having 2 to about 6 amino groups and containing about 24 to 50 carbons; (b) N,N'-disalicylidine-1,2-propylenediamine, and (c) a cyclohexylamine selected from the group consisting of N,N-dimethyl-cyclohexylamine and dicyclohexylamine.
U.S. Pat. No. 3,355,490, Van Munster, teaches a process for the manufacture of N-alkyl-(or N,N-dialkyl)-cyclohexylamines such as N-methylcyclohexylamine and N,N-dimethylcyclohexylamine and mentions their use as fuel oil additives with no specifics as to the function of the additive in the fuel oil given.
U.S. Pat. No. 4,040,799, Oude Alink et al., discloses the use of N-methylcyclohexylamine, N,N-dimethylcyclohexylamine, and alkyl substituted derivatives of these amines as fuel additives for stabilizing distillate fuels.
U.S. Pat. No. 4,163,646, Oude Alink et al., discloses N,N'-substituted diamines such as N,N'-substituted 2,4-diamino-2-substituted pentanes, wherein the nitrogen function is disubstituted, as fuel stabilizers.
Suggestions of the prior art for stabilizing fuel oils also include U.S. Pat. No. 2,256,187, Bartram, which discloses the use of a condensation product of a phosphorous halide and an organic hydroxyl containing compound, with the preferred class of materials comprising esters of phosphorus acids, to increase the stability of a relatively unstable oil product. Also, U.S. Pat. No. 2,261,227, Cloud, discloses the use of certain organic phosphites as stabilizing ignition promoters of diesel fuel.
The combination of amines and phosphates as additives for various distillate fuels is common in the prior art. U.S. Pat. No. 2,297,114, Thompson, discloses the use of a primary, secondary, or tertiary alkyl amine or an organic ester of phosphoric acid to prevent deterioration of gasoline when exposed to sunlight. U.S. Pat. No. 2,863,904, Cantrell et al., teaches the use of primary N-alkyl amines and di-oxo-octyl acid phosphates in mineral oil compositions to protect metal surfaces from rust or corrosion. U.S. Pat. No. 3,359,083, Von Allmen, discloses a primary amine with hydrocarbyl phosphinic acid to furnish anti-icing and anti-stalling properties to motor fuel compositions. U.S. Pat. No. 3,387,954, Capowski et al., discloses that quaternary amines with the anion being a phosphoric acid radical stabilize liquid hydrocarbon fuels against sediment formation and corrosion. U.S. Pat. No. 3,389,980, Kautsky, discloses the use of primary, secondary, or tertiary alkyl orthophosphoric acid salts of a branched-chain alkyl amine in gasoline to reduce deposits and icing in carburetors.
A monophosphate ester and a diamine, containing both a primary and a secondary amine, were disclosed as a detergent in gasoline in U.S. Pat. No. 3,639,110, Larson. The same combination was disclosed as an anti-icing agent in U.S. Pat. No. 3,771,980, Larson.
Dispersion of particulate matter in distillate products was accomplished with a combination of an amine (primary, secondary, or tertiary) and a phosphate as taught by U.S. Pat. No. 3,751,236, Adams. U.S. Pat. No. 3,895,925, Schlicht et al., teaches the use of an alkyl ammonium alkyl alkanephosphonate as an anti-icing agent and as a corrosion inhibitor for motor fuels. U.S. Pat. No. 3,909,214, Polss, teaches a combination of monoamine salts of branched chain primary alkyl acid esters of orthophosphoric acid and liquid polypropylene controls deposits in engines. U.S. Pat. No. 4,002,437, Broeckx et al., teaches the use of a mixture of a polymeric acid, an amine salt of an oxyo-alkyl acid ester or ortho-phosphoric acid, an aliphatic ester demulsifier and a saturated hydrocarbon solvent to prevent lacquer deposition in diesel fuel engines.
The mixture of the mono- and di-alkyl phosphates and the reaction product of epichlorohydrin with hydrogenated tallow amine was disclosed to prevent deposit formation during the processing, transportation, storage, and/or use of hydrocarbon oils in U.S. Pat. No. 3,017,357, Cyba which is incorporated by reference herein.
In the processing of crude oils, organic esters of phosphates and phosphites with amines have been disclosed as inhibiting and supressing fouling as taught in U.S. Pat. Nos. 4,024,048, 4,024,050, 4,024,051, Shell et al., and 4,542,253, Kaplan et al.
However, none of these prior art references disclose the unique and effective mixture of a phosphite ester compound and a tertiary amine or the reaction product of tallow amine and epichlorohydrin in accordance with the instant invention for inhibiting the color degradation and particulate formation of distillation fuel oils.